function set_pos(var xx, var yy, var r)
{
	int cho=integer(random(60));
	if(my.sayac==1)
				{
					my.y=random((2*r))-r;
					//my.x=random(2*r)-r;
					if(cho>=30)
					my.x=sqrt(r*r-my.y*my.y);
					else
					my.x=-sqrt(r*r-my.y*my.y);
					
					my.sayac=0;
				}
}
